Clear ice maker

ABSTRACT

The present invention is a clear ice maker with an expansion space in a tapered cup below a similarly tapered ice mold. The expansion space forces the mold to lift relative the cup when freezing is complete. Sawtooth protrusions in the cup may be provided to enable line contact between the cup and mold. The mold is easy to remove from the cup to release the ice shape.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to ice cube trays intended for household and business use, and in particular related to ice trays with multiple chambers that enable clear or transparent ice to be made.

Description of the Background Art

An example of a clear ice cube tray of this known type is disclosed in U.S. Pat. No. 5,364,063 (Nishimura), which consists of an inner tray divided into plural numbers of cubic pockets with an open top, and of an outer tray configured such that the inner tray fits within the outer tray, with a space to be formed, when assembled, between the outer bottom of the inner tray and the inner bottom of the outer tray, with openings provided on the bottom of the inner tray to allow water access to the space so as to make transparent ice in the cubic pockets. The water in such an ice tray freezes top to bottom, beginning from the open top surface and gradually proceeding downwards through the cubic pocket and into the reservoir below. This gradual directional freezing allows air and impurities to be pushed downward into the reservoir between the inner and outer trays, leaving the upper cubic pocket containing clarified ice.

Other types of clear ice cube trays employ a similar methodology to Nishimura, but substitute the use of a single ice pocket or mold in place of a tray, which allows for different shapes of clear ice to be made, with openings at the top and bottom of said mold to facilitate top to bottom directional freezing.

A common problem with prior art clear ice makers is that the clarified ice is typically very difficult to extract from its mold or tray. Traditional methods of extracting ice, such as using flexible ice trays or molds made from flexible material, typically do not work well as the ice typically “sticks” to the walls of its tray or mold. In some cases the inner and outer tray components or molds also freeze together, creating a frozen mass that must be loosened by running hot water over the surface, or broken apart with brute force.

A need therefore exists for an improved clear ice maker where clear ice cubes are easy to extract from the molds.

SUMMARY OF THE INVENTION

The present invention provides a solution to the problem of extracting clarified ice from an ice maker by using the expansive forces of the freezing ice within the reservoir to “self-extract” the clarified ice cubes from the tray by pushing their individual molds directionally upwards, thus breaking contact with the sidewall of the inner tray and creating a much smaller surface area for the mold to “stick” to. A series of protrusions along the sidewall of the inner tray also aids in breaking the surface area contact of the mold with the sidewall as expansion takes place. The result is clarified ice that can be neatly extracted from the ice tray with minimal time and effort.

It is another object of the invention to provide an improved clear ice maker where various shapes and sizes of ice can be formed within an easily extractable ice mold, allowing for a plurality of different and customizable ice “cube” designs which can all benefit from the self-extracting expansive ice properties of the invention. The mold is hemispherically divided and made from a flexible material to facilitate easy removal of the clarified ice inside by simply peeling the two halves apart. In some embodiments the two halves are completely separable. In other embodiments the two halves are connected by a thin strip of flexile material on the bottom surface which allows the mold to be pulled apart without splitting both halves completely.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention and its advantages will be apparent from the Detailed Description taken in conjunction with the accompanying Drawings, in which:

FIG. 1 is a top perspective view of clear ice maker constructed in accordance with the invention;

FIG. 2 is a bottom perspective view of the clear ice maker of FIG. 1;

FIG. 3 is an exploded perspective view of the clear ice maker;

FIG. 4 is an inner perspective view of an ice mold half used in the clear ice maker;

FIG. 5 is an outer perspective view of the ice mold half of FIG. 4;

FIG. 6 is top view of the clear ice maker;

FIG. 7 is a cross-section taken along lines 7-7 of FIG. 6;

FIG. 8 is a cross-section taken along lines 8-8 of FIG. 6; and

FIGS. 9A-9D are schematic views of the clear ice maker in operation.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-9D, where like numerals indicate like and corresponding elements, a clear ice maker 10 includes an outer container 12 formed of polystyrene foam in the preferred embodiment, though other thermal insulating materials can be used with equivalent effect. Walls 14 (FIG. 3) in the outer container 12 define a top opening 16 in communication with an inner cavity 18. While a clear ice maker with two identical such cavities is described, it will be readily understood that a device with a single cavity could also be used, or the device could be scaled up to include any number of cavities desired.

A receiver 20 is formed of a rigid material, which is preferably a molded thermoplastic. As best shown in FIG. 3, receiver 20 is removably located within the inner cavities 18 of the outer container 12. Receiver 20 is removable from outer container 12 only as a matter of convenience, because the two parts are made separately of different materials. It is possible, however, to fix receiver 20 in outer container 12, for example with adhesive or physical locking structure, or to mold a unitary structure having the requisite thermal insulating and rigidity properties of outer container 12 and receiver 20.

The receiver 20 has at least one cup 30 formed by interior side walls 32 (FIGS. 7,8), an interior bottom wall 34, and edges 36 (FIG. 3) defining an open top 38. The cup interior side walls 32 are tapered outwardly from the interior bottom wall 36 to the open top 38. The cup interior side walls 32 also have a plurality of sloping, horizontal, shallow sawtooth protrusions 40 (FIGS. 7,8), spaced about 4 mm apart and having a depth of about 0.2 mm.

An ice mold 50 is formed of a suitable material, which is preferably pliable but could also be non-pliable, and more preferably is a silicone rubber having a Shore A durometer in the range of about 30 to about 40. The ice mold 50 consists of two mirror-image halves 52 inserted into the cup 30. The ice mold 50 further includes exterior side walls 54 tapered for close, parallel interfitment with the tapered cup interior side walls 32 adjacent the sawtooth protrusions 40. The ice mold also has a bottom exterior wall 56, with stiffening buttresses 58 and walls 60 forming a drain hole. Ice mold 50 includes interior walls 62 which will be shaped in any number of possible ways to define the desired shape of the resulting clear ice, which could include traditional cubes as illustrated, or spheres, polyhedrons or other shapes.

The cup 30 and ice mold 50 are sized to provide an expansion space 70 in a lower section 72 of the cup 30 below the bottom exterior wall 56 of the ice mold. The expansion space 70 is sized to lift the ice mold 50 relative the cup 30 when water in the expansion space 70 freezes into ice. The relative sizing of the expansion space and the ice mold, which determines the amount of lift and thereby the desired degree of loosening of the mold in the cup, can be determined by routine experimentation.

In operation, as shown in FIGS. 9A-9D, two of the pliable mold halves 52 are placed firmly into the rigid cup 30 of the receiver 20. The receiver 20 is inserted into the insulating outer container 12. As shown in FIGS. 9A and 9B, water 80 is placed into the top of each mold 50 until it and the expansion space 70 below are full.

The clear ice maker 10 is then put into a freezer and left overnight, as illustrated in FIG. 9C. It generally takes at least 13 hours to freeze completely, but this time will vary between differently shaped and sized clear ice makers and freezer temperatures. The water 80 in the mold will freeze from top to bottom, with ice 82 above still unfrozen water 80. As is well known with this type of ice maker, the purpose of the insulating outer container 12 is to provide thermal insulation on all sides except the top, which enables the top-down freezing progression.

As shown in FIG. 9D, when the last of the water 80 is frozen into ice 82 at the bottom of the expansion space 70, the expansion of the ice pushes the mold 50 up just enough (dimension “N”) to free it from the grip of the tapered receiver cup 30. (Dimension N is exaggerated in FIG. 9D for clarity.) Dissolved gases and impurities 84 have been pushed down out of the mold, so the resulting ice shape is perfectly clear. Mold 50 is easily removed from the receiver cup 30, and the two halves 52 are separated from the clear ice shape.

The easy removal of the mold from the receiver cup, enabled by the expansion space, is what distinguishes this invention from all other known clear ice makers using top-down freezing. The sawtooth protrusions also enable the molds to break free a little easier than without, which would be a smooth-walled cup. The protrusions create line contact with the mold exterior when the mold is lifted, as opposed to sheets of ice in the spaces between the cup and mold which would fiercely grip the mold. The line contacts of the protrusions are like a tear strip on a piece of paper that helps when separating a portion of paper from the whole. Also, the protrusions will hold the silicone molds in place a little longer during the freezing process, then allow the molds to “pop” up when the expanding ice creates enough pressure to do so. The protrusions, especially the lower ones, will also act as a seal that will not allow the water to flow up the outside of the silicone mold during filling. This will aid in reducing the amount of water between the side walls of the molds and cups.

Thus, it is seen that the provision of expansion spaces in the tapered cups, below tapered ice molds, results in a substantial improvement over all the other known clear ice makers where the mold freezes to its container and is very difficult to pull loose. In contrast, when the freezing is done with the present invention, it is easy to just pull out the molds and open them.

Whereas, the present invention has been described with respect to a specific embodiment thereof, it will be understood that various changes and modifications will be suggested to one skilled in the art, and it is intended to encompass such changes and modifications as fall within the scope of the appended claims. 

I claim:
 1. A clear ice maker, comprising: an outer container formed of a thermal insulating material and having walls defining a top opening in communication with an inner cavity; a receiver formed of a rigid material and located within the inner cavity of the outer container; the receiver having at least one cup formed by interior walls and edges defining an open top; an ice mold inserted into the cup, and having a bottom exterior wall; and with the cup and ice mold sized to provide an expansion space in a lower section of the cup below the bottom exterior wall of the ice mold, the expansion space sized to lift the ice mold relative the cup when water in the expansion space freezes into ice.
 2. The clear ice maker of claim 1 with the insulating material being polystyrene foam.
 3. The clear ice maker of claim 1 with the receiver being removably located in the inner cavity.
 4. The clear ice maker of claim 1 with the receiver being fixed in the inner cavity.
 5. The clear ice maker of claim 1 with cup interior side walls being tapered outwardly from an interior bottom wall to the open top.
 6. The clear ice maker of claim 1 with the cup interior walls including side walls having a plurality of sloping, horizontal, shallow sawtooth protrusions.
 7. The clear ice maker of claim 6 with the sawtooth protrusions spaced about 4 mm apart and having a depth of about 0.2 mm.
 8. The clear ice maker of claim 1 with the ice mold formed of pliable material.
 9. The clear ice maker of claim 1 with the ice mold consisting of two mirror-image halves inserted into the cup.
 10. The clear ice maker of claim 1 with the ice mold further including exterior side walls tapered for parallel interfitment with tapered cup interior side walls.
 11. The clear ice maker of claim 6 with the ice mold further including exterior side walls tapered for parallel interfitment with tapered cup interior side walls adjacent the sawtooth protrusions.
 12. A clear ice maker, comprising: an outer container formed of a thermal insulating material and having walls defining a top opening in communication with an inner cavity; a receiver formed of a rigid material and located within the inner cavity of the outer container; the receiver having at least one cup formed by interior walls and edges defining an open top; an ice mold inserted into the cup, and having a bottom exterior wall; with cup interior side walls being tapered outwardly from an interior bottom wall to the open top; with the cup interior side walls having a plurality of sloping, horizontal, shallow sawtooth protrusions; and with the ice mold further including exterior side walls tapered for parallel interfitment with the tapered cup interior side walls; and with the cup and ice mold sized to provide an expansion space in a lower section of the cup below the bottom exterior wall of the ice mold, the expansion space sized to lift the ice mold relative the cup when water in the expansion space freezes into ice.
 13. The clear ice maker of claim 12 with the insulating material being polystyrene foam.
 14. The clear ice maker of claim 12 with the receiver being removably located in the inner cavity.
 15. The clear ice maker of claim 12 with the receiver being fixed in the inner cavity.
 16. The clear ice maker of claim 12 with the sawtooth protrusions spaced about 4 mm apart and having a depth of about 0.2 mm.
 17. The clear ice maker of claim 12 with the ice mold formed of pliable material.
 18. The clear ice maker of claim 17 with the ice mold formed of pliable silicone rubber having a Shore A durometer in the range of about 30 to about
 40. 19. The clear ice maker of claim 12 with the ice mold consisting of two mirror-image halves inserted into the cup.
 20. A clear ice maker, comprising: an outer container formed of polystyrene foam and having walls defining a top opening in communication with an inner cavity; a receiver formed of a rigid material and removably located within the inner cavity of the outer container; the receiver having at least one cup formed by interior side walls, an interior bottom wall, and edges defining an open top; the cup interior side walls being tapered outwardly from the interior bottom wall to the open top, and the cup interior side walls having a plurality of sloping, horizontal, shallow sawtooth protrusions spaced about 4 mm apart and having a depth of about 0.2 mm; an ice mold formed of pliable silicone rubber having a Shore A durometer in the range of about 30 to about 40, the ice mold consisting of two mirror-image halves inserted into the cup, the ice mold further including exterior side walls tapered for parallel interfitment with the tapered cup interior side walls adjacent the sawtooth protrusions, and the ice mold having a bottom exterior wall; and with the cup and ice mold sized to provide an expansion space in a lower section of the cup below the bottom exterior wall of the ice mold, the expansion space sized to lift the ice mold relative the cup when water in the expansion space freezes into ice. 